Title:	Global visibility
Authors:	Trefný, Marek Bittner, Jiří
Citation:	Journal of WSCG. 1997, vol. 5, no. 1-3.
Issue Date:	1997
Publisher:	Václav Skala - UNION Agency
Document type:	článek article
URI:	http://wscg.zcu.cz/wscg1997/wscg97.htm http://hdl.handle.net/11025/15923
ISSN:	1213-6972 (print) 1213-6980 (CD-ROM) 1213-6964 (online)
Keywords:	globální viditelnost;VRML;prostorové dělení
Keywords in different language:	global visibility;VRML;spatial subdivision
Abstract in different language:	Virtual reality applications such as architectural walkthroughs require a powerful graphics hardware to achieve interactive frame rates of rendering. Usual rendering algorithms like z-buffer or BSP-tree often spend significant time processing portions of model that are currently invisible to an observer. To describe restrictions in visibility, the visibility information can be precomputed and used to dramatically reduce amount of data to be processed during rendering. The model of a virtual environment is divided into cells using an algorithm of spatial subdivision. The spatial subdivision is represented by a graph structure. For each cell the cell-to-cell and cell-to-frustum visibility information is determined and stored in a tree data structure within that cell. However, widely used languages for description of model geometry, such as VRML, do not offer resources to describe the scene subdivision and to store the explicit visibility information along with the geometry. This article discusses some solutions that were chosen during the global visibility research project at the Department of Computer Science and Engineering at FEE CTU in Prague.
Rights:	© Václav Skala - UNION Agency
Appears in Collections:	Volume 5, number 1-3 (1997)

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